1. Field of the Invention
This invention relates to the field of electronics packaging, and in particular, to high-density electronic modules for housing and interconnecting electronic components located on stacked substrate layers.
2. Description of the Related Art
Increasing the volume density of electronic packaging is crucial for reducing device sizes for a given functionality. Efforts to provide high-density electronic packaging have included three-dimensional stacking technology in an attempt to avoid the inherent geometric constraints of standard two-dimensional semiconductor integrated circuits (xe2x80x9cICsxe2x80x9d). By stacking electronic modules on top of one another and providing interconnections between the modules, the multiple layers can provide additional circuit elements without extending the two-dimensional footprint beyond that of a single module. Certain embodiments have also included heat-conducting, electrically insulating layers to improve heat dissipation during operation of these stacked electronic modules.
Numerous packaging schemes have been developed for stacking silicon-based ICs to increase the volume densities of electronic devices. However, while the silicon wafers of the silicon-based ICs provide rigidity and stability for the electronic elements, the ultimate volume densities of the multilayer stacks are inherently limited due to the thicknesses of the silicon wafers. Lapping off excess silicon from the back side of silicon wafers before stacking has been used to decrease the thickness of the silicon layers, and hence increase the number of layers per unit height. However, this procedure is time-consuming and requires precise machining to avoid damaging the circuit elements.
In accordance with one aspect of an embodiment of the invention, a multilayer module has a plurality of active layers wherein each active layer has a flexible substrate therein. The multilayer module comprises a first active layer with a first edge. The active layer comprises a flexible, polymer substrate, at least one electronic element, and a plurality of electrically-conductive traces which provide electrical connection from the first edge to the electronic element of the first active layer. The multilayer module further comprises a second active layer with a second edge. The second active layer comprises a flexible, polymer substrate, at least one electronic element, and a plurality of electrically-conductive traces which provide electrical connection from the second edge to the electronic element of the second active layer. The second active layer is adhered to the first active layer so that the first edge and second edge are aligned with each other thereby forming a side of the multilayer module. The multilayer module further comprises a plurality of electrically-conductive lines along the side of the multilayer module, the lines providing electrical connection to the traces.
In accordance with another aspect of an embodiment of the invention, a method provides electrical connection to a plurality of electronic elements. The method comprises providing a first active layer The first active layer has a first edge and comprises a flexible, polymer substrate, at least one electronic element, and a plurality of electrically-conductive traces which provide electrical connection from the first edge to the electronic element of the first active layer. The method further comprises adhering a second active layer to the first active layer. The second active layer has a second edge and comprises a flexible, polymer substrate, at least one electronic element, and a plurality of electrically-conductive traces which provide electrical connection from the second edge to the electronic element of the second active layer. The first edge and second edge are aligned with each other thereby forming a side of the multilayer module. The method further comprises applying a plurality of electrically-conductive lines along the side of the multilayer module. The lines provide electrical connection to the traces.
In accordance with another aspect of an embodiment of the invention, a multilayer module has a plurality of active layers wherein each active layer has a flexible substrate therein. The multilayer module comprises a first active layer with a first edge. The first active layer comprises a flexible, polymer substrate, at least one electronic element, and a plurality of electrically-conductive traces which provide electrical connection from the first edge to the electronic element of the first active layer. The multilayer module further comprises a second active layer with a second edge. The second active layer comprises a flexible, polymer substrate, at least one electronic element, and a plurality of electrically-conductive traces which provide electrical connection from the second edge to the electronic element of the second active layer. The second active layer is adhered to the first active layer so that the first edge and second edge are aligned with each other thereby forming a side of the multilayer module. The multilayer module further comprises a segmentation layer adhered to the second active layer. The segmentation layer comprises a thermally-conductive material. The multilayer module further comprises a plurality of electrically-conductive lines along the side of the multilayer module. The lines provide electrical connection to the traces.
In accordance with another aspect of an embodiment of the invention, a method provides electrical connection to a plurality of electronic elements. The method comprises providing a first active layer The first active layer has a first edge and comprises a flexible, polymer substrate, at least one electronic element, and a plurality of electrically-conductive traces which provide electrical connection from the first edge to the electronic element of the first active layer. The method further comprises adhering a second active layer to the first active layer. The second active layer has a second edge and comprises a flexible, polymer substrate, at least one electronic element, and a plurality of electrically-conductive traces which provide electrical connection from the second edge to the electronic element of the second active layer. The first edge and second edge are aligned with each other thereby forming a side of the multilayer module. The method further comprises adhering a segmentation layer to the second active layer. The segmentation layer comprises a thermally-conductive material. The method further comprises applying a plurality of electrically-conductive lines along the side of the multilayer module. The lines provide electrical connection to the traces.
In accordance with another aspect of an embodiment of the invention, a multilayer module has a plurality of layers wherein each layer has a flexible substrate therein. The multilayer module comprises a first layer having a top side and bottom side. The first layer comprises a flexible, polymer substrate, at least one electronic element, and a plurality of electrically-conductive traces. The multilayer module further comprises a second layer having a top side and bottom side. The second layer comprises a flexible, polymer substrate, at least one electronic circuit, and a plurality of electrically-conductive traces. The bottom side of the second layer is adhered to the top side of the first layer. The thickness of the combination of the first and second layers is less than or equal to approximately 0.005xe2x80x3.
In accordance with another aspect of an embodiment of the invention, a method provides electrical connection to a plurality of electronic elements. The method comprises providing a first layer having a top side and bottom side. The first layer comprises a flexible, polymer substrate, at least one electronic element, and a plurality of electrically-conductive traces. The method further comprises providing a second layer having a top side and bottom side. The second layer comprises a flexible, polymer substrate, at least one electronic element, and a plurality of electrically-conductive traces. The method further comprises adhering the bottom side of the second layer to the top layer of the first layer. The thickness of the combination of the first and second layers is less than or equal to approximately 0.005xe2x80x3.
In accordance with another aspect of an embodiment of the invention, a multilayer module has a plurality of electrical elements. The multilayer module is fabricated by a process comprising providing a plurality of active layer sheets. Each active layer sheet comprises a flexible, non-electrically-conductive substrate sheet and a plurality of arrayed active areas with borders of adjacent arrayed active area defining dicing lines. Each active area comprises at least one electronic element and a plurality of electrically-conductive traces which provide electrical connection from an edge of the arrayed active area to the electronic element. The process further comprises providing a plurality of segmentation layer sheets. Each segmentation layer sheet comprises a flexible, non-electrically-conductive substrate sheet and a plurality of arrayed segmentation areas with borders of adjacent arrayed segmentation areas defining dicing lines. Each segmentation area comprises a thermally-conductive material. The process further comprises stacking a plurality of active layer sheets upon one another with adhesive between the active layer sheets. The arrayed active areas of the active layer sheets are aligned in registry with one another. The process further comprises stacking at least one segmentation layer sheet with the plurality of active layer sheets with adhesive between the segmentation layer sheet and the active layer sheets. The dicing lines of the segmentation layer sheet are in registry with the dicing lines of the active layer sheets, thereby assembling an arrayed module pre-form corresponding to an arrayed multilayer module. The process further comprises stacking a plurality of arrayed module pre-forms. The arrayed module pre-forms are oriented with at least one segmentation layer sheet between each pair of arrayed module pre-forms and with a thermoplastic adhesive material applied to the segmentation layer sheets, thereby assembling a stack of arrayed module pre-forms. The process further comprises applying pressure and heat to the stack of arrayed module pre-forms to laminate the active layer sheets and the segmentation layer sheets together, thereby forming a stack of arrayed multilayer modules. The process further comprises cutting the stack of arrayed multilayer modules along the dicing lines, thereby dividing the stack of arrayed multilayer modules into stacks of multilayer modules having sides formed by edges of the active areas and segmentation areas. The process further comprises forming electrically-conductive lines along at least one side of the stack of multilayer modules. The lines provide electrical connection to the traces. The process further comprises segmenting the stack of multilayer modules into individual multilayer modules by displacing the multilayer modules relative to one another while applying heat to the thermally-conductive material to release the thermoplastic adhesive.
In accordance with another aspect of an embodiment of the invention, a multilayer module has a plurality of electronic elements. The multilayer module comprises a plurality of flexible support means. Each flexible support means supports at least one of the plurality of electronic elements. The multilayer module further comprises means for stacking and adhering said flexible support means to one another. The multilayer module further comprises means for providing electrical connection to the electronic elements.
In accordance with another aspect of an embodiment of the invention, a multilayer module has a top layer and a bottom layer. The multilayer module comprises a plurality of flexible active layers. Each active layer comprises a non-electrically-conductive first substrate with an edge, at least one electronic element, and a plurality of electrically-conductive traces which provide electrical connection from the edge of the first substrate to the electronic element. The active layers are laminated together so that the edges of the first substrates form a side of the multilayer module and the traces of the active layers are aligned in registry with one another. The multilayer module further comprises a plurality of electrically-conductive lines along the side of the multilayer module. The lines provide electrical connection to the traces. The multilayer module further comprises at least one flexible segmentation layer laminated to the active layers. The segmentation layer comprises a non-electrically-conductive second substrate and a thermally-conductive material. The segmentation layer is either the top layer or the bottom layer of the multilayer module.
For the purposes of summarizing the invention, certain aspects, advantages and novel features of the invention have been described herein above. It is to be understood, however, that not necessarily all such advantages may be achieved in accordance with any particular embodiment of the invention. Thus, the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.